A wellbore or borehole is generally drilled into the ground to recover natural deposits of hydrocarbons and/or other desirable materials trapped in a geological formation in the Earth's crust. The wellbore or borehole is typically drilled using a drill bit attached to a lower end of a drill string. The wellbore or borehole may be drilled to penetrate subsurface geological formation in the Earth's crust that contain the trapped hydrocarbons and/or other materials. As a result, the trapped hydrocarbons and/or materials may be released and/or recovered via the wellbore or borehole.
A bottom hole assembly (hereinafter “BHA”) is typically located at the lower end of the drill string and includes the drill bit along with one or more sensors, control mechanisms and/or circuitry. Traditionally, the one or more sensors of the BHA detects or measures one or more downhole measurements associated with one or more properties of the subsurface geological formation and/or fluid or gas contained within the formation. Additionally, the one or more sensors of the BHA detects or measures one or more downhole measurements associated with an orientation and/or a position of the BHA and the drill bit with respect to the subsurface geological formation, the natural deposits of hydrocarbons, other materials, and/or the surface of the Earth.
Drilling operations for the drill bit located at the BHA of the drill string are controlled by one or more operators located at the Earth's surface or at an operations support center located locally or remotely with respect to the well, borehole and/or the drill string. The drill string is rotated at a rotational rate by a rotary table, or a top drive located at the Earth's surface. The one or more operators controls the rotational rate, an amount of weight-on-bit and/or other operating parameters associated with the drilling process.
Drilling fluid is pumped from the Earth's surface to the drill bit via an interior passage of the drill string. The drilling fluid cools and lubricates the drill bit during the drilling process. Additionally, the drilling fluid transports drill cuttings from the geological formations by the drill bit, uphole to the Earth's surface.
To facilitate successful and desirable drilling operations for the borehole, the one or more operators must have access to and/or be aware of the downhole measurements made by the one or more sensors of the BHA. In order for the one or more operators to access the downhole measurements for controlling and/or steering the drill bit and/or a direction of the drill bit, a communication link must be established and/or provided between the one or more operators at the Earth's surface and the BHA of the drill string. A “downlink” is known to be a communication link extending downhole from the Earth's surface to the BHA of the drill string. Based the downhole measurements collected at the BHA, the one or more operators transmit commands downhole to the BHA via the downlink to steer the drill string.
An “uplink” is known to be a communication link uphole from the BHA of the drill string to the Earth's surface. An uplink is typically a transmission of the data and/or information associated with the one or more downhole measurements which may be detected, measured and/or collected by the one or more sensors located at the BHA. For example, it is often important for an operator to know the orientation of the BHA with respect to the formation. Thus, orientation data and/or measurements detected and/or collected by one or more sensors located at the BHA is transmitted uphole from the BHA to the Earth's surface via the uplink.
A known telemetry system for providing communication (i.e., downlink and/or uplink communications) between the Earth's surface and the BHA is mud pulse telemetry. Mud pulse telemetry is a method of sending or transmitting data, one or more commands and/or one or more measurements via one or more signals, either downlink or uplink communications, by creating one or more pressure and/or flow rate pulses (hereinafter “pressure pulses”) in the drilling mud. A pattern of pressure pulses, such as a frequency, a phase, and/or an amplitude, is representative of the data, the one or more commands and/or one more measurements received or transmitted by the one or more operators located at the Earth's surface to the BHA. The pattern of pressure pulses is detected by at least one sensor of the BHA via downlink communications or by at least one sensor at the Earth's surface via uplink communications. The pattern of pressure pulses is interpreted by the at least one sensor and/or a processor such that the data, the one or more commands and/or the one or more measurements is understood by the processor, the BHA and/or the operators located at the Earth's surface.
Often, the one or more commands and/or one or more measurements which are represented by the pattern of pressure pulses include a large quantity of data. In order to transmit a large quantity of data, it is generally known to compress the large quantity of data into a smaller quantity of data via one or more data compression techniques. Then, the smaller quantity of compressed data may be transmitted between locations more efficiently and/or more effectively. However, known data compression techniques utilized in, for example, audio and/or video data compression do not perform with the low bandwidth and high noise level associated with the communication link between the Earth's surface and the BHA. As a result, known data compression techniques are not suitable for use with the communication link between the Earth's surface and the BHA. Moreover, known data compression techniques do not adequately compress large quantities of data and/or measurements collected downhole. As a result, large quantities of data and/or measurements collected downhole are unable to be transmitted uphole to the Earth's surface or are inaccurately and/or ineffectively transmitted uphole to the Earth's surface.